1. Field of the Invention
This invention relates to cameras and, more particularly, to a camera which uses a roll film received within a Patrone (cartridge) and which is provided with a film feeding device for winding and rewinding the film.
2. Related Art And Prior Art Statement
Conventionally, a camera which uses a roll film received within a cartridge is arranged such that the cartridge is loaded into a camera body, idle films of first two or three frames are wound around a winding spool and, thereafter, the film is taken up about the winding spool after each photographing operation, the photographed film is rewound again into the cartridge after photographing, and the cartridge is taken out of the camera body. As a film feeding device which performs film winding operation and film rewinding operation, various kinds of film feeding devices have been considered such as one in which rotational force of a motor or the like is transmitted to a winding spool through a clutch, gears or the like to wind the film, and the clutch is changed over to rotate a rewinding shaft within the cartridge to rewind the film. As the publicly known techniques, there is one disclosed, for example, in Japanese Utility Model Laid-Open No. SHO 60-21734 (21734/1985) or Japanese Patent Laid-Open No. SHO 57-89735 (89735/1982).
A film winding and rewinding mechanism disclosed in Japanese Utility Model Laid-Open No. SHO 60-21734 (21734/1985) is arranged such that resistant force is applied with respect to a rotational direction of a motor which is arranged laterally, and a linear direction of a helical gear is changed over in accordance with the orientation of the relative driving, whereby rotational driving force is transmitted to the winding side and the rewinding side of the film, and the rotational driving force is transmitted to the film winding spool and a film rewinding fork by conversion of a rotational direction due to a bevel gear to wind and rewind the film.
Meanwhile, a film feeding system disclosed in Japanese Patent Laid-Open No. SHO 57-89735 adopts an arrangement in which a driving motor is mounted within a spool chamber, all of the film within the cartridge is previously wound around a spool side before photographing is started, and the film is rewound into the film cartridge through one frame each photographing operation. The winding and rewinding operations are such that the driving force of the motor is directly transmitted to the spool to wind the film, and the driving force of the motor is transmitted to the rewinding fork through the bevel gear via a planetary clutch to rotate the cartridge shaft to rewind the film into the cartridge.
Since, however, the means disclosed in Japanese Utility Model Laid-Open No. SHO 60-21734 uses a helical gear which is used as a clutch, and a bevel gear used for conversion of an angle of the rotary shaft, uses are different from each other, the number of parts increases and, accordingly, a large space is required within the camera body for these components. Thus, efficiency is low. Moreover, since the resistance force is given to the rotational direction of the helical gear in order to produce thrust force in an axial direction, the means has a disadvantage that the efficiency is further low.
Meanwhile, means disclosed in Japanese Patent Laid-Open No. SHO 57-89735 is arranged such that a planetary clutch is used for changing-over of winding and rewinding, and a shaft having bevel gears at both ends is used only for transmission of rewinding power. Accordingly, uses of the respective parts are distinct or separate from each other. Thus, the means has problems that the number of parts increases and the cost increases.
By the way, transmission mechanisms having worm wheels and worm gears have conventionally been proposed variously. For example, a transmission mechanism is used in a motor assembly or the like of a motor driving camera disclosed in Japanese Patent Laid-Open No. SHO 54-41607 (41607/1979). Further, regarding a bearing for a support or pivot shaft for a gear, there is one disclosed in Japanese Patent Publication No. SHO 54-9489 (9489/1979).
Conventionally, as the worm wheel and the worm gear which are used as the transmission mechanism for the power, a worm wheel 31 and a worm gear 33 which are made of metal are used as shown in FIG. 6 of the attached drawings. The metallic worm wheel 31 is formed into configuration great in thickness in radial direction, and a pivot shaft which is small in diameter is fitted in a cylinder in a center of the worm wheel 31.
However, in recent years, the worm wheel 31 is molded in order to reduce the cost. However, the conventional arrangement has the following disadvantages. That is, if the worm wheel 31 is manufactured by molding, gear accuracy and shaft-and-bore accuracy become low because the pivot shaft 32 of the worm wheel 31 is fitted in a cylinder and the worm wheel 31 is great in thickness in a radial direction.
Furthermore, the arrangement has the following disadvantages. That is, consideration is given to the bearing 34 for the worm gear 33. Since the bearing 34 in which the pivot shaft 33a for the worm gear is rotatably fitted and is supported receives a planar forward-end surface of the pivot shaft 33a by a planar surface 36, frictional resistance is large or high so that efficiency is reduced.
Accordingly, in order to remove the disadvantages, an arrangement has been proposed in which, as shown in FIG. 7, a steel ball 35 is arranged within the bearing 34 for the pivot shaft 33a of the worm gear 33, and the forward-end surface of the pivot shaft 33a of the worm gear 33 is received by the steel ball 35. However, this means has a disadvantage that parts increase in number, and assembling is also complicated.
Moreover, conventionally, technical means in which a rotational shaft of a motor is supported by two points and is rotated has been proposed in Japanese Patent Application No. SHO 54-41607 (41607/1979). Furthermore, a mechanism in which a rotational shaft of a sprocket is supported by two points, and is rotated by a gear attached to the sprocket is disclosed in Japanese Patent Laid-Open No. SHO 62-187332 (187332/1987).
However, in a case of the technical means disclosed in Japanese Patent Application No. SHO 54-41607, there is a fear that, when a large or high load is applied to the worm gear, the shaft may bend because of the two-point support. Further, in a case of the technical means disclosed in Japanese Patent Laid-Open No. SHO 62-187332, there is a fear that, when an excessive load is applied in a direction opposite to the rotational direction of the sprocket upon winding, the rotational shaft for the sprocket may bend because the rotational shaft for the sprocket a two-point support.
Meanwhile, various transmission mechanisms for a driving force of the camera which winds and rewinds the film, and a lens frame is moved by means of a single rotational driving source have conventionally been proposed.
As an example of such driving-force transmission mechanism for a camera, an arrangement is disclosed in, for example, Japanese Patent Application No. HEI 4-060548 (060548/1992) in which gears to be driven are selected by rotation of a sun gear in one direction by means of a planetary-gear changing-over mechanism, and are driven by rotation in the other direction.
Moreover, Japanese Patent Laid-Open No. SHO 61-172127 (172127/1986) has disclosed an arrangement in which, In a planetary-gear changing-over mechanism, electromagnetic engaging means is used to be engaged with revolution of a planetary gear, to transmit rotational driving force in opposite directions of a sun gear.
However, since the arrangement disclosed in Japanese Patent Application No. HEI 4-060548 (060548/1994) can transmit only rotation in one direction when the gear to be driven is driven by the sun gear, it is impossible to normally and reversely drive the single gear system. In a case where this is improved so that normal and reverse rotations are transmitted to two locations, four (4) gears in mesh with the planetary gear are required in view of a mechanism. This is a disadvantage in small-sizing or miniaturizing applications.
Furthermore, the arrangement disclosed in Japanese Patent Laid-Open No. SHO 61-172127 (172127/1986) has a problem that electromagnetic engaging means is required in order to cause the sun gear to be engaged so that the cost increases.